Republican Sen. John Cornyn challenged Obama’s assertion that America must close the prisoner facility at Guantanamo Bay, insisting it remains crucial to U.S. national security.

“Gitmo serves as an important function of detaining America’s most dangerous enemy combatants,” Cornyn said in a statement. “No individual who continues to pose a threat to the U.S. should be shuttled home at the expense of American taxpayers only to return to the battlefield to kill Americans and our friends, no matter how many dramatic hunger strikes are staged.”

Sen. John Cornyn on “Face the Nation” (AP Photo/CBS, Chris Usher)

Obama called on Congress to close the prison, which he promised in 2008 that he would close during his first year in office. Now well into his sixth year, Obama blamed the facility’s continued existence on Congress and said “there is no justification beyond politics for Congress to prevent us from closing a facility that should never have been opened.”

Austin Rep. Mike McCaul, chairman of the House Homeland Security committee, said Obama can’t ignore the fact that al Qaeda continues to pose as a threat to America and that closing Guantanamo would increase that threat.

“The Obama administration’s return to a pre-9/11 counterterrorism mindset puts American lives at risk,” he said. “This war will continue whether the president acknowledges it or not.”

Cornyn called the president’s speech an attempt to “pivot from scandals” and said American safety should be the president’s “foremost consideration.”

President Obama also attempted to redefine the post-9/11 area of national security and the fight against global terrorism.

“America is at a crossroads. We must define our effort not as a boundless ‘global war on terror’ – but rather as a series of persistent, targeted efforts to dismantle specific networks of violent extremists that threaten America,” he said.

Obama pledged to set more narrow parameters on the use of drones abroad to limit the causalities, which he said is a haunting reality of war.

“Before any strike is taken, there must be near-certainty that no civilians will be killed or injured — the highest standard we can set,” he said.

Rep. Mac Thornberry holds up a newspaper during a House hearing. (AP Photo/Kenneth Lambert)

West Texas Rep. Mac Thornberry plugged his national security oversight bill in the House and said it would be wise of Obama to come out in support of the legislation.

“If the president would have done something like that it would go a long way to gain bipartisan trust,” Thornberry, a Republican from Clarendon, told CNN’s Jake Tapper.

Thornberry sits on a handful of national security-related House committees, including Vice Chairman of the House Armed Service committee and a member of the House Select Committee on Intelligence.

Obama’s remarks on drones comes only a day after the administration released information that four Americans had been killed, all known terrorists, in drone strikes since 2009.

Thornberry’s bill, which has bipartisan support, would mandate congressional oversight by defense committees of any lethal defense operations, including drone activity, overseas.

Obama did allude to possibly supporting an effort to create an additional independent oversight during his speech, though he said Congress has been notified of every drone strike.

Thornberry said support from Obama on additional oversight would assure the American people “that somebody else is looking at this.”